1. Field of the Invention
The present invention relates in general to microwave ovens, and more particularly to a microwave oven having high-power output switching means capable of controlling the maximum power output of the oven according to allowable current of a distribution board.
2. Description of the Prior Art
Microwave ovens are generally adapted to perform a cooking operation based on a super-high frequency, in a different manner from cooking equipment of an external heating type based on thermal conduction and thermal radiation. Such a conventional microwave oven comprises a super-high frequency oscillation tube, or a magnetron, for generating a super-high frequency of 2,450 MHz in response to high-voltage power applied thereto. The super-high frequency of 2,450 MHz generated from the magnetron causes an electric field to turn in direction at a rate of 2.45 billion times per second. Where this super-high frequency is applied to food, molecules of water in the food vibrate at a rate of 2.45 billion times per second while generating a large amount of heat, thereby cooking the food.
In the above-mentioned conventional microwave oven, allowable current is fixed at a predetermined value in a hardware manner, so the maximum power consumption of the microwave oven, related to the maximum power output thereof, is set to a certain value below power consumption based on the allowable current value.
For example, assuming allowable current of a home distribution board is 15A, microwave oven oscillatable current of about 13.8A is obtained by subtracting hood motor current consumption of about 0.6A and hood lamp current consumption of about 0.6A from the allowable current value. In this case, power consumption of the microwave oven is 1656 Watts if an input voltage is 120V and a power factor is 0.95. The maximum power output of the microwave oven is theoretically 950 Watts if efficiency is 60%.
In other words, in the conventional microwave oven, allowable current is fixed at a predetermined value in a hardware manner, thereby making it impossible for the microwave oven to output its maximum power higher than a predetermined value even though allowable current of a home distribution board is set to a greater value. That is, it is impossible for the microwave oven to change its maximum power output according to given situations.
Therefore, the present invention has been made in view of the above problem, and it is an object of the present invention to provide a microwave oven having high power output switching means capable of controlling the maximum power output of the oven according to allowable current of a distribution board.
In accordance with the present invention, the above and other objects can be accomplished by the provision of a microwave oven comprising a magnetron for generating a high frequency in response to a high voltage; a transformer having primary and secondary coils, the transformer generating the high voltage in a turn ratio of the primary and secondary coils and supplying a to the magnetron; and high-power output switching means for controlling the level of a voltage applied to the primary coil of the transformer.